1. Field of the Invention
The present invention relates to a system for the control of the amount of fuel to be injected in an internal combustion engine. The system according to the present invention is applicable to a diesel engine for an automotive vehicle having a spill mechanism acting to stop the fuel supply to the fuel injection nozzle in the engine.
2. Description of the Prior Art
In general, where a conventional VE type fuel injection pump is used as a fuel injection pump in an internal combustion engine for an automotive vehicle, the start of fuel injection is decided by a timer in the VE pump. The termination of fuel injection is decided by the detection of a reference signal and a phase signal by sensors in the VE pump, and a spill start signal from a computer is supplied to an electromagnetic valve.
In engines having the above-described fuel amount control system, a problem exists in that, when there are variations in the response characteristic of the electromagnetic valve, the characteristic of the fuel injection amount is also subject to variation. It has been confirmed by the present inventors that the response characteristic of an electromagnetic valve is such that an approximately constant time delay occurs in each of the electromagnetic valves regardless of the engine rotational speed or the fuel injection amount.
Also, when the above-described fuel amount control system is used for an engine having multiple cylinders, if the spill start signals for the engine cylinders are delivered at the same angle, the fuel injection amount is subject to variation due to the phase shift of a face cam of the VE pump. It has been confirmed by the present inventors that an approximately constant time delay occurs in each of the cylinders regardless of the engine rotational speed or the fuel injection amount.